Image Sensor Fabrication via Dummy Pattern Etch Control
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Solution Overview
Problem
The existing process for forming normal contact holes in micro-electronic systems, such as image sensors, often results in incomplete etching of the interlayer dielectric layer, leading to electrical connection issues due to the formation of an insulation film after the super-contact hole, which requires deeper etching and can cause connectivity problems.
Innovation Solution
A method involving the formation of spacers and a dummy pattern on the semiconductor substrate, followed by a metal pad for electrical connections, allowing the interlayer dielectric layer to be etched only up to the metal pad, thereby avoiding the need for deeper etching and ensuring proper electrical connections without altering the etching depth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an insulation film is formed after the super-contact hole formation, then the super-contact is shielded and protected, but the interlayer dielectric layer requires deeper etching which causes incomplete etching and electrical connection problems
Solution Approach 1:
The dummy pattern is formed in advance on the interlayer dielectric layer before the insulation film is deposited. This preliminary structure serves as a depth reference that prevents over-etching when normal contact holes are formed later, ensuring that the etching stops at the appropriate depth to maintain electrical connection reliability without compromising the shielding function of the insulation film.
2Ease of manufacture
If the interlayer dielectric layer is etched deeper to account for the insulation film, then the normal contact hole can penetrate through, but the etching becomes incomplete and causes electrical connection issues
Solution Approach 1:
The dummy pattern acts as an intermediary reference structure between the insulation film and the etching process. It provides a physical depth marker that mediates the etching depth control, allowing the process to achieve both adequate penetration through the insulation film and precise stopping at the correct depth to avoid electrical connection problems.
Data Source
AI summary
A method for fabricating an image sensor includes at least one of: (1) Forming a gate on a semiconductor substrate; (2) Forming spacers on both side walls of the gate and forming a dummy pattern on an upper portion of the semiconductor substrate; and (3) Forming a metal pad for an electrical connection on an upper portion of the dummy pattern. The method may include at least one of: (1) Forming an interlayer dielectric layer covering the entire semiconductor substrate, (2) Etching portions of the interlayer dielectric layer and the semiconductor substrate to form a super-contact hole; and (3) forming an insulation film on the entire surface of the interlayer dielectric layer. The method may include forming normal contact holes such that a portion of an upper portion of the gate and a partial region of the metal pad for an electrical connection are exposed and filling up the normal contact holes with a conductive material to form normal contacts.